Space Tech Peers Inward

Computer software developed by NASA’s Jet Propulsion Laboratory (JPL) has made it possible to peer into the human body with greater accuracy. The new noninvasive imaging technology, an outgrowth of JPL’s work on processing images from distant planets, makes it possible to pinpoint potential problems in arteries long before they produce any detectable symptoms.

Visible walls: An image produced by ArterioVision software shows the exact thickness of the inner layers of the carotid artery wall (highlighted in red) by automatically detecting the boundaries between brightness levels in the interior of the vessel (dark region at top) and in the muscle (lighter area below) more accurately than traditional, manual methods.

The software system, called ArterioVision, is designed to work with ultrasound equipment that most hospitals already have to produce accurate images of any narrowing of the carotid arteries in the neck. Such narrowing can be a warning sign of developing atherosclerosis, or hardening of the arteries.

Robert Seltzer, who worked at JPL developing image-processing software from the 1960s until his retirement in 2002, says the image-processing software was originally designed to enhance some of the earliest images sent back from lunar and planetary probes. But NASA realized early on that the same processing could be applied to medical imaging, and it began a variety of research projects to develop those applications.

At first, NASA tried using software to enhance x-ray images but found that it wasn’t very useful because the original images were already highly detailed. Later work led to the development of ways of enhancing ultrasound images, which have lower resolution but have the advantage of not exposing patients to the risks of radiation.

Recently approved by the FDA, JPL’s software makes it possible to detect not only the inner wall of the arteries, but also the actual thickness of the innermost two layers of the arterial wall itself, called the intima and the media. The system focuses on the carotid arteries because they are close to the surface and easily detected using the noninvasive ultrasound method. A thickening of the arterial wall there is generally an indicator of a progressive thickening of the arteries elsewhere in the body. And unlike traditional methods using x-ray based CT scans, the test can be safely and easily repeated to monitor how well the patient is responding to any combination of lifestyle changes and medication. This allows the doctor and the patient to adjust the treatment over time as they see what actually works for the latter.

The test takes only a few minutes, with the patient lying on an examining table as the doctor runs the ultrasound device over both sides of the neck, following a prescribed pattern to scan the arteries. The software then constructs a detailed picture of the arteries and calculates the thickness of the intima and the media.

Without the JPL software, a technician would visually scan an ultrasound image on a computer screen and manually delineate the arterial wall by moving a mouse. This manual approach is subjective, hence findings from a single image can vary unpredictably. Seltzer says that in tests in which 100 patients were scanned once and then tested again a week later, the consistency of the thickness readings from one week to the next was four to ten times better with the software than with manual tracking. “When you come in on different days, you get the same result,” he says.

Howard Hodis of the Keck School of Medicine at the University of Southern California, who conducted some of the clinical trials, says that “once patients see how thick their arteries are, there is much more incentive for them to change their lifestyle” by making alterations to their eating habits and exercise level.

The JPL-developed software has been licensed to a company called Medical Technologies International, which is now making it available to hospitals everywhere. The company’s president, Gary Thompson, says he became interested in marketing the software after he learned firsthand how well it could reveal problems in patients who had no detectable symptoms.

Thompson says that he has a family history of heart disease, so when he turned 50, he paid for an expensive and exhaustive battery of tests–which he passed with flying colors. But weeks later, while running a marathon, he suddenly had a heart attack.

After recovering, he heard about the new software that was undergoing clinical trials, and he decided to give it a try. “I walked in, and I didn’t tell them I had had a heart attack, didn’t tell them anything about the family history,” Thompson says. “In 15 minutes, after a $500 test, they told me, ‘You need to see the doctor immediately.’”

Years later, clinical trials have now established that this was not an isolated event and that, as illustrated by Thompson’s own experience, “in many cases, it will identify people who are at risk even when they are completely asymptomatic,” he says. “For 40 percent of people who ultimately die of a heart attack, the first symptom is death. It happens all the time.” Thompson hopes the new technology will help change that.